Another thought: Not sure I agree with the statement that the bigger army almost always won and there were no random influences. Hattin, anyone? Outbreaks of "plague" at most sieges? The rallying of the Christian defenders at Antioch, after finding the holy lance and seeing St Michael lead the heavenly host against the Saracens? Sure, faulty strategical decisions, the lack of hygiene, and starvation/exhaustion would be more accurate parameters than random events. Still, the combat interface should be kept fairly simple, so some random events might be worth considering, to add flair.
I believe Chris King's reply is based on the ambition to make a great game. The typical crusading commander influenced his army in two main ways - maneuvering to get favourable terrain advantages, and holding his knights back from charging for as long as possible - preferrably until just the right time. If you fought at all. Most armies simply marched around the countryside, eventually entering into a siege - since you needed castles to control the land, and committing to a battle meant risking the whole campaign. Numbers ofc played in, but not necessarily to the exlusion of morale, war exhaustion, the promise of plunder, religious fervour and other factors.
That said, as far as I'm concerned I'd prefer a balanced and enjoyable game true to the spirit of the times, rather than a exhaustingly detailed, slow historical simulator.